Add doc strings

src/classes/pgmq.ts

@@ -13,6 +13,8 @@ interface DbMessage {
   message: string
 }
 
+/** This is the central class this library exports
+ * @constructor requires a valid PG connection string. Example: postgresql://user:password@localhost:5432/pgmq  **/
 export class Pgmq {
   private pool: Pool
 
@@ -26,6 +28,10 @@ export class Pgmq {
     await connection.query(query)
   }
 
+  /**
+   * Creates a queue and a matching archive if does not exist. If queue or archive already exist does not throw error
+   * @param name - the name of the queue
+   * **/
   public async createQueue(name: string) {
     const connection = await this.pool.connect()
     const query = `
@@ -50,6 +56,10 @@ export class Pgmq {
     connection.release()
   }
 
+  /**
+   * Deletes a queue and its matching archive if exists. If queue or archive do not exist does not throw error
+   * @param name - the name of the queue
+   * **/
   public async deleteQueue(name: string) {
     const connection = await this.pool.connect()
     const query = `
@@ -59,11 +69,16 @@ export class Pgmq {
     connection.release()
   }
 
-  public async sendMessage<T>(
-    queue: string,
-    message: T,
-    vt = 0
-  ): Promise<number> {
+  /**
+   * Write a message to the queue.
+   * If queue doesn't exist, will throw error. See [createQueue]{@link createQueue} 
+   * @param queue - the name of the queue to send the message to.
+   * @param message - the object to put as the payload of the message.
+   * @param vt - the visibility timeout of the message. The visibility timeout 
+   * defines the time a message will stay hidden after being saved.
+   * @return the id of the message that was created
+   * **/
+  public async sendMessage<T>(queue: string, message: T, vt = 0) {
     const connection = await this.pool.connect()
 
     const query = `INSERT INTO ${PGMQ_SCHEMA}.${QUEUE_PREFIX}_${queue} (vt, message)
@@ -74,27 +89,37 @@ export class Pgmq {
     return parseInt(res.rows[0].msg_id)
   }
 
-  public async readMessage<T>(
-    queue: string,
-    vt: number
-  ): Promise<Message<T> | null> {
+  /**
+   * Read a message from the queue
+   * @param queue - the name of the queue
+   * @param vt - the visibility timeout of the message. The visibility timeout
+   * defines the time a message will stay hidden after being retrieved, allowing other
+   * consumers to process it later if it was not removed from the queue
+   * @return the whole [message]{@link Message}, including the id, read count and the actual message within 
+   */
+  public async readMessage<T>(queue: string, vt: number) {
     const connection = await this.pool.connect()
     const query = `WITH cte AS
-                                (SELECT msg_id
-                                 FROM ${PGMQ_SCHEMA}.${QUEUE_PREFIX}_${queue}
-                                 ORDER BY msg_id ASC
-                                 LIMIT 1 FOR UPDATE SKIP LOCKED)
-                       UPDATE ${PGMQ_SCHEMA}.${QUEUE_PREFIX}_${queue} t
-                       SET vt      = now() + interval '${vt} seconds',
-                           read_ct = read_ct + 1
-                       FROM cte
-                       WHERE t.msg_id = cte.msg_id
-                       RETURNING *;`
+                            (SELECT msg_id
+                             FROM ${PGMQ_SCHEMA}.${QUEUE_PREFIX}_${queue}
+                             ORDER BY msg_id
+                             LIMIT 1 FOR UPDATE SKIP LOCKED)
+                   UPDATE ${PGMQ_SCHEMA}.${QUEUE_PREFIX}_${queue} t
+                   SET vt      = now() + interval '${vt} seconds',
+                       read_ct = read_ct + 1
+                   FROM cte
+                   WHERE t.msg_id = cte.msg_id
+                   RETURNING *;`
     const msg = await connection.query(query)
     connection.release()
     return this.parseDbMessage<T>(msg.rows[0])
   }
 
+  /**
+   * Delete a message from the queue
+   * @param queue - the name of the queue
+   * @param id - the id of the message to delete
+   */
   public async deleteMessage(queue: string, id: number) {
     const query = `DELETE
                        FROM ${PGMQ_SCHEMA}.${QUEUE_PREFIX}_${queue}
@@ -106,6 +131,11 @@ export class Pgmq {
     return parseInt(msg.rows[0].msg_id)
   }
 
+  /**
+   * Archives a message from the queue to its matching archive
+   * @param queue - the name of the queue / archive
+   * @param id - the id of the message to delete
+   */
   public async archiveMessage(queue: string, id: number): Promise<number> {
     const query = `WITH archived AS (
             DELETE FROM ${PGMQ_SCHEMA}.${QUEUE_PREFIX}_${queue}